In the present proposal, the major purpose will be to test whether there is a correspondence between animals and humans in terms of prefrontal cortex mediation of memory function. It has been proposed that the basic deficit in humans with prefrontal cortex damage is the inability to order information on a short-term temporal basis. This is based on both clinical observations and deficits on cognitive tests in which prospective functions dealing with memory for relative recency are measured. Previous research has suggested that the prefrontal cortex in rats mediates temporal structuring of information, suggesting a correspondence between animals and humans. In order to elaborate further on the role of the prefrontal cortex in processing temporal information, suggesting a correspondence between animals and humans. In order to elaborate further on the role of the prefrontal cortex in processing temporal information, a behavioral model has been developed in rats in which one can measure a) memory for order information for a list of specific visual cues, b) memory for order information for a list of specific motor responses, c) memory for frequency, d) utilization of retrospective and prospective codes in remembering lists of spatial locations. It is proposed to use this animal model as a means of continuing the investigation of the role of prefrontal cortex in mediating temporal ordering of information. The first aim is to determine whether the medial prefrontal cortex in the rat mediates temporal (order) information for specific visual cues as well as for specific motor responses. The second aim is to determine whether the medial prefrontal cortex in the rat mediates memory for frequency. The third aim is to determine whether the medial prefrontal cortex is involved with retrospective and prospective coding of sequential information. The fourth aim is to determine possible uniqueness of function of the medial prefrontal cortex by examining the role of the orbito-insular prefrontal cortex, dorsolateral frontal cortex and parietal cortex in mediating temporal information. It is hoped that the information gleaned from these studies will provide an understanding of the frontal lobe syndrome such that a rational therapeutic intervention can be established.